Display device and timepiece comprising a wiring board layered on a back surface of a back substrate

ABSTRACT

A display device that has a display panel having a front substrate, an image forming unit, and a back substrate rendered together in layers, and a wiring board layered on the back surface of the back substrate. A plurality of input/output pins are formed on the front surface of the back substrate, and a plurality of connection pins that are electrically connected to the input/output pins by respective conductor members are formed on the back surface of the wiring board.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority under 35U.S.C. §120 on, U.S. application Ser. No. 12/257,942, filed on Oct. 24,2008, the contents of which are incorporated by reference herein. Thisapplication also claims priority under 35 U.S.C. §119 on Japanese PatentApplication No. 2007-290684, which is also incorporated by reference inits entirety.

BACKGROUND

1. Field of Invention

The present invention relates to a display device and a timepiece.

2. Description of Related Art

A display device according to the related art as depicted in JapaneseUnexamined Patent Appl. Pub. JP-A-2007-133182 bonds the terminalportions of a wiring board overlapping the conductor portions of thedisplay panel disposed outside the display area. These conductorportions and wiring board each have a plurality of pins, and adhesion byan anistropic conductive film is used to connect the pins of theconductor portion with the pins of the wiring board.

The display panel has a top substrate, a transparent electrode formed onthe top substrate, a bottom substrate on which the pixel electrodes areformed, and an image forming layer including liquid crystals orelectrophoretic particles rendered between the transparent electrode andthe pixel electrodes. The image forming layer is sealed by epoxy, forexample, disposed along the outside edge of the image forming layersealing the gap between the top and bottom substrates.

A flexible circuit board is often used for the wiring board. The wiringboard extends substantially along the display surface of the displaypanel from the end of the conductor portions of the display panel towhich it is connected. The plural pins disposed to the other end of thewiring board are connected to a device-side circuit board by connectors.

In the construction of the related art in which the display panel andwiring board are connected between the plane surfaces thereof, asubstrate connection portion for connecting the display panel and thewiring board is required outside the image display area of the displaypanel.

This substrate connection area must be outside the sealing member forreasons including conduction stability, and the size of the frame areasurrounding the image display area is increased by the size of this sealplus the size of the substrate connection area. This degrades theappearance and increases the size of the device in which the displaydevice is incorporated by the area of this frame.

Because the display module including the top substrate, image forminglayer, and back substrate is separate from the wiring board, the housingstructure for the display module and wiring board each take up spaceinside the device. This is particularly disadvantageous in devices inwhich space is at a premium, such as in a wristwatch.

In order to save space the flexible wiring board connected to the pinsof the display panel could be folded over to overlap the back side ofthe display panel. However, the wiring board can only be folded over inthis manner when the display panel and wiring board are sufficientlyseparated, and this actually requires even more space.

Because the wiring board and display panel are connected in the planedirection, the pins on the main circuit board of the device disposed onthe back side of the display panel and the pins of the wiring board mustnormally be connected together by connectors. This means that the pinpositions of the display device must correspond to the pin positions ofthe device, and wide applicability is thus impaired.

Furthermore, when the pins of the wiring board and the pins of thedevice-side circuit board are connected by individual connectors,connecting and disconnecting the wiring board from the device-sidecircuit board during initial assembly and after-sale service isdifficult.

SUMMARY OF INVENTION

A first aspect of the invention is a display device that enablesnarrowing the frame area around the image display area while alsoreducing the space needed for installation in a device or product,improves the utility of the positions of the pins connected to thedevice-side circuit board, and affords easier connection anddisconnection of the display device to the device-side circuit board.Another aspect of the invention is a timepiece having this displaydevice.

A first aspect of the invention is a display device having a displaypanel having a front substrate, an image forming unit, and a backsubstrate rendered together in layers, and a wiring board layered on theback surface of the back substrate. A plurality of input/output pins areformed on the front surface of the back substrate, and a plurality ofconnection pins that are electrically connected to the input/output pinsby respective conductor members are formed on the back surface of thewiring board.

By rendering the display panel and wiring board layered together, theinput/output pins on the front of the back substrate and the connectionpins can be electrically connected through the thickness of the backsubstrate by suitable conductor members such as wiring members or leads.More specifically, the display panel and wiring board in this embodimentof the invention are not connected in the plane direction, a connectionarea between the ends of the wiring board and the display panel is notneeded outside the image display area, and only enough area for theinput/output pins and the connection pins is needed outside the imagedisplay area. As a result, the area outside the image display area, thatis, the frame portion, can be extremely narrow.

Furthermore, by rendering the display panel and the wiring board as asingle module, less space is needed to house them inside a product.

In addition, by layering the wiring board with the display panel, thepins connected to the product-side circuit board can be formed at anysuitable position on the back side of the wiring board, and the displaydevice of the present invention can be easily assembled into a widerange of products and devices. Appropriately positioning the pins alsohelps to reduce the product size.

By forming the connection pins on the back side of the wiring board, theconnection pins and the pins of the device-side circuit board can beelectrically connected through a conductive member rising vertically tothe back surface of the wiring board, for example. Because the displaypanel and wiring board are also rendered as a single module as astand-alone component, removing the display device from and installingthe display device to a product during after-sales service is simple.

A glass epoxy circuit board that is less expensive than a flexiblecircuit board can also be used for the wiring board.

In a display device according to another aspect of the invention theimage forming unit is preferably formed containing electrophoreticparticles.

This aspect of the invention helps to further reduce the size andthickness of the display device and the device or product in which thedisplay device is used by combining the thinness of an electrophoreticdisplay with the narrow frame portion described above.

The appearance can also be further improved by rendering a narrow framearound an electrophoretic display, which can be used for a highcontrast, high resolution display.

Yet further preferably, the conductor members are bonding wires.

By using bonding wires, this aspect of the invention enables connectingthe input/output pins formed on the front side of the back substratewith the connection pins formed on the back side of the wiring board inless space in the plane direction of the display panel. As a result, theframe portion can be rendered even narrower.

Yet further preferably, the image forming unit is sealed between thefront substrate and the back substrate by a sealing member disposed inan area including the outside edge part of the image forming unit, andthe sealing member covers the conductor members.

By using the same sealing member to seal the image forming unit and theconductor members, this aspect of the invention further simplifies theconstruction.

In another aspect of the invention the wiring board is a double-sidedcircuit board having conductors on both front and back surfaces, and theconnection pins have through-holes passing through the wiring board.

By thus using a double-sided circuit board (which includes multilayercircuit boards) for the wiring board, more electronic components can beeasily mounted than if a single-sided circuit board is used.

In addition, the input/output pins formed on the front side of the backsubstrate and the connection pins formed on the back side of the wiringboard can be easily interconnected through through-holes.

Further preferably, a drive circuit that drives the display panel isdisposed on the back surface of the wiring board.

Compared with the display panel drive circuit being mounted on adevice-side circuit board, this aspect of the invention shortens thelength of the wiring pattern connecting the display panel to the drivecircuit, thereby reduces conductive resistance, and thus reduces powerconsumption.

The connection pins connected through the through-holes to the back sideof the wiring board are connected to this drive circuit.

Yet further preferably, a temperature sensor is disposed on the backsurface of the wiring board.

This aspect of the invention can ensure the display quality of thedisplay panel by controlling driving the display panel according to thetemperature detected by the temperature sensor.

The invention is thus particularly effective when applied to anelectrophoretic display, the display characteristics of which are easilyaffected by changes in temperature.

The temperature sensor is preferably disposed at a positioncorresponding to the image forming unit.

In another aspect of the invention the display device is incorporated ina product, a circuit board of the product is disposed on the backsurface side of the wiring board, the wiring board and the circuit boardare pressed together with an elastic connector therebetween, and theconnector includes a conductor connecting the connection pins and thecircuit board, and a dielectric elastic body.

Because the circuit board of the product in which the display device isincorporated is disposed to the back side of the wiring board, theconnection pins and the pins of the circuit board can be easilyinterconnected by positioning the connector between the wiring board andthe circuit board. This aspect of the invention stabilizes electricalconductivity by pressing the wiring board and the circuit board togetherwith the elastic connector therebetween by a spring, for example.

In according to another aspect of the invention

a plurality of connection pins corresponding to the same input/outputpins are formed in each of a first position and a second position on theback surface of the wiring board, and a first pin group composed of aplurality of connection pins formed at the first position, and a secondpin group composed of a plurality of connection pins formed at thesecond position, are formed on the back surface of the wiring board.

This aspect of the invention enables selecting the pin group thatconnects easily to the device-side pins from among the plural pingroups. More specifically, because the positions of the device-side pinsare not limited to a specific position, the general applicability of thedisplay device of the invention can be improved.

The invention is not limited to two pin groups, and three or more pingroups may be formed at mutually different positions on the back side ofthe wiring board.

Another aspect of the invention is a timepiece having the display devicedescribed above, and a circuit board located on the back surface side ofthe wiring board of the display device.

By using the display device described above, this aspect of theinvention achieves the same operation and effect described above.

A timepiece according to another aspect of the invention has a handattached to a shaft passing in the thickness direction through thedisplay panel and the wiring board, and a drive wheel train that isdisposed between the wiring board and the circuit board and drives thehand.

By layering the wiring board with the display panel, the membersupporting the parts of the movement, including the drive wheel train,other wheel trains, and levers, can be disposed on the back side of thewiring board. This enables more efficiently arranging the parts in acombination timepiece in which an analog time display using hands iscombined with digitally displaying content on a display panel, and thedisplay panel also functions as a dial.

Further preferably, the timepiece also has a position detection sensorthat is disposed on the back surface of the wiring board and detects therotational position of a wheel contained in the drive wheel train or awheel that moves in conjunction with the drive wheel train.

By thus locating the wiring board in the area on the drive wheel trainside of the display device, the position detection sensor can be easilydisposed near the wheel of which the position is to be detected.

The position detection sensor is used, for example, to detect when thetime goes to the hour from the rotational position of the wheel, and isused to correct the displayed time based on the internal clock.

As described above, the invention enables reducing the width of theframe margin around the image display area, reduces the required housingspace inside a device or product in which the display device is used,increases the utility of the pin positions, and makes connecting anddisconnecting the display device to the device-side circuit boardsimple.

Other objects and attainments together with a fuller understanding ofthe invention will become apparent and appreciated by referring to thefollowing description and claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side section view of a timepiece according to a firstembodiment of the invention.

FIG. 2 is a side section view of the same timepiece.

FIG. 3 is a schematic plan view of a display device incorporated in thetimepiece.

FIG. 4 is a section view through line X-X′ in FIG. 3.

FIG. 5 is a section view through line Y-Y′ in FIG. 3.

FIG. 6 is a schematic plan view from the back side of the wiring boardin a first variation of the first embodiment of the invention.

FIG. 7 is a schematic section view of a display device according to asecond embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the invention is described next with reference toFIG. 1 to FIG. 5. Note that in the following embodiments parts that arefunctionally the same as parts that have already been described areidentified by the same reference numerals and further descriptionthereof is omitted.

FIG. 1 and FIG. 2 are side section views of a timepiece according to thepresent invention. The timepiece according to this embodiment of theinvention is a combination watch having analog hands 11 for displayingthe time and a digital display device 2. This timepiece has a base plate12, a drive wheel train 13 and stepping motor 14 supported on the baseplate 12, a circuit board 15 and a movement 10 including a battery 16disposed on the opposite side of the base plate 12 as the display device2, a case 17 housing the movement 10 and the display device 2, a backcover 18, and a crystal 19.

The display device 2 and the movement module 101 are held together inunison by a panel pressure spring 101A.

The circuit board 15 is populated with a timekeeping circuit including acrystal oscillator circuit and a frequency dividing circuit, a controlIC, and capacitors. The circuit board 15 is assembled in unison with themovement module 101 by a circuit pressure spring 101B.

FIG. 3 is a plan view of a rectangular display device 2. FIG. 4 is asection view through line X-X′ in FIG. 3, and FIG. 5 is a section viewthrough line Y-Y′ in FIG. 3.

In the following description of the display device 2, the “top” side orsurface is the side on the top or front as seen in 4 and FIG. 5, and the“bottom” side or surface is the side on the bottom or back as seen in 4and FIG. 5.

The display device 2 includes a display panel 20 and a wiring board 30disposed on the back side of the display panel 20. The display panel 20is a matrix drive electrophoretic display device in this embodiment ofthe invention. The display panel 20 and wiring board 30 are renderedlayered together in a single module. A through-hole 201 through whichpasses the shaft 110 of the wheel and pinion to which the hands 11 arefastened (FIG. 4 and FIG. 5) is rendered in the center part of thedisplay panel 20 and the wiring board 30. The area around thethrough-hole 201 is sealed with a sealant 202 (FIG. 4, FIG. 5) such asan epoxy resin.

The invention is not limited to an electrophoretic display device, andmay be a liquid crystal display (LCD) or electroluminescent (ED) displaydevice.

The display panel 20 in this embodiment of the invention is a layeredconstruction including a front or top substrate 21, an electrophoreticlayer 22 as an image forming unit, and a TFT (thin film transistor)layer 23 as a back substrate.

Note that in this embodiment of the invention the display panel 20 has adigital display function for displaying text, graphics, and images, andalso functions as a timepiece dial. More specifically, the markers towhich the hands 11 point are displayed on the display panel 20.

The top substrate 21 includes a polyethylene terephthalate (PET) sheet211 and a common electrode (transparent electrode) 212 rendered by anITO (indium tin oxide) coating applied to the back side of the PET sheet211. Numerous microcapsules 220 rendering the electrophoretic layer 22are attached by an adhesive or an adhesive film to the top substrate 21in this embodiment of the invention. The area in which the microcapsules220 are disposed is the image display area 200 of the display panel 20shown in FIG. 3. A frame area 200Z surrounds the outside of the imagedisplay area 200.

A crystal 213 is bonded to the top surface of the top substrate 21.

Charged black electrophoretic particles and white electrophoreticparticles that are charged oppositely to the black electrophoreticparticles are contained inside the microcapsules 220 of theelectrophoretic layer 22. The microcapsules 220 are shown in FIG. 4 andFIG. 5 much larger than actual size.

A sealant 24 such as an epoxy resin disposed around the outside edgeportion of the electrophoretic layer 22 seals the electrophoretic layer22 between the top substrate 21 and a TFT circuit board 23. Theelectrophoretic layer 22 is thus protected from humid environments andchange in the characteristics of the electrophoretic particles issuppressed.

The sealant 24 is disposed to the back side of the crystal 213, aroundthe edge portion of the top substrate 21, and on the top surface of theTFT circuit board 23, thereby assuring a tight seal.

The TFT circuit board 23 includes a glass substrate 231, pixelelectrodes rendered in a matrix pattern on the top surface of the glasssubstrate 231, and a TFT layer 232 containing thin-film transistors. Thedisplay panel 20 in this embodiment of the invention is TFT driven, buta TFD (thin-film diode) drive method may be used instead.

A y-axis drive unit 232Y (FIG. 4), an x-axis drive unit 232X (FIG. 5), acommon electrode conductor unit 232COM (FIG. 5), and a plurality ofinput/output pins 233 (FIG. 5) are rendered on the front surface 23A ofthe TFT circuit board 23. The y-axis drive unit 232Y is connected toeach of the source lines disposed on the y-axis of the pixel electrodes.The x-axis drive unit 232X is connected to each of the gate linesdisposed on the x-axis of the pixel electrodes. The common electrodeconductor unit 232COM is connected through a conductive member 212A(FIG. 5) to the common electrode 212. The input/output pins 233 areconnected to each of the drivers in the x-axis drive unit 232X, y-axisdrive unit 232Y, and common electrode conductor unit 232COM. As shown inFIG. 3, the input/output pins 233 are arrayed along one short side ofthe TFT circuit board 23.

The wiring board 30 is a double-sided glass epoxy circuit board that isattached to the back side 23B of the TFT circuit board 23 by an adhesiveor an adhesive film.

As shown in FIG. 5, a plurality of patterns 31A that are electricallyconnected to the input/output pins 233 by bonding wires 25 are formed onthe front side 30A of the wiring board 30.

The bonding wires 25 bend from the front surface 23A of the TFT circuitboard 23 through the thickness of the TFT circuit board 23 to the backside 23B, and are affixed by alloy bonding to the input/output pins 233and patterns 31A.

Note that on the one short side of the display panel 20 to which thebonding wires 25 are disposed the sealant 24 is disposed along the edgepart of the TFT circuit board 23 and the front side 30A of the wiringboard 30 so that the bonding wires 25 are coated and isolated from eachother by the sealant 24.

A plurality of connection pins 31 that are electrically connectedthrough through-holes 31B to the patterns 31A on the front side 30A areformed on the back side 30B of the wiring board 30. A rubber connector32 is disposed between the connection pins 31 and the circuit board 15(FIG. 1), and the connection pins 31 are electrically connected by therubber connector 32 to the power supply block and control circuit uniton the circuit board 15, and to the display panel 20 drive circuitmounted on the circuit board 15.

While not shown in detail, the rubber connector 32 has a plurality ofconductors connecting the connection pins 31 to the circuit board 15,and a dielectric rubber elastic body that isolates the conductors fromeach other. The rubber connector 32 is compressed between the wiringboard 30 and circuit board 15 by the panel pressure spring 101B (FIG. 1,FIG. 2), thereby stabilizing conduction between the connection pins 31and circuit board 15.

The effect of this embodiment of the invention is described next.

(1) The display panel 20 and wiring board 30 of the display device 2 arelayered together and the input/output pins 233 on the front surface 23Aof the TFT circuit board 23 are electrically connected to the connectionpins 31 by bonding wires 25 passing through the thickness of the TFTcircuit board 23. The display device 2 thus constructed does not need abonding area between the display panel 20 and wiring board 30 outsidethe image display area 200, and requires only enough space for theinput/output pins 233 and the connection pins 31 that are connected bythe bonding wires 25 outside the image display area 200, and the framearea 200Z can therefore be quite narrow.

(2) By rendering the display panel 20 and the wiring board 30 as asingle module, less space is needed to house them inside the timepiececase 17.

Rendering the display panel 20 and the wiring board 30 as a singlemodule also makes removing and installing the display device 2 duringafter-sales service simple.

(3) By layering the wiring board 30 with the display panel 20, theconnection pins 31 can be formed at any suitable position on the backside 30B of the wiring board 30, and the display device 2 can be easilyassembled into a wide range of timepiece models. Appropriatelypositioning the pins also helps to reduce the timepiece size.

(4) The connection pins 31 and the pins of the circuit board 15 can beeasily electrically connected through the rubber connector 32 by formingthe connection pins 31 on the back side 30B of the wiring board 30. Morespecifically, by simply placing the display device 2 on the movement 10and engaging the panel pressure spring 101A with the outside edge partof the base plate 12, the connection pins 31 and circuit board 15 can bereliably electrically connected through the rubber connector 32.

(5) By using bonding wires 25 for conductivity between the input/outputpins 233 and connection pins 31, the input/output pins 233 formed on thefront surface 23A of the TFT circuit board 23 and the connection pins 31formed on the back side 30B of the wiring board 30 can be rendered inless space in the plane direction of the display panel 20 than ispossible using a lead harness. This enables further reducing the widthof the frame area 200Z.

(6) The sealant 24 is used to seal the electrophoretic layer 22 and toseal the bonding wires 25, thereby simplifying construction.

(7) Conduction between the connection pins 31 and circuit board 15 isstabilized as a result of pressing the wiring board 30 and circuit board15 together with the rubber connector 32 therebetween by the panelpressure spring 101A.

First Variation of the First Embodiment

FIG. 6 shows the back side 40B of the wiring board 40 in a firstvariation of the first embodiment. A plurality of connection pins 31arrayed as a first pin group G1 in a direction along a short side of thewiring board 40, and a plurality of connection pins 31 arrayed as asecond pin group G2 in a direction along a long side of the wiring board40, are disposed to the back side 40B of the wiring board 40. Thesefirst and second pin groups G1 and G2 include connection pins 31 for thesame input/output pins 233.

This configuration enables selecting the group of pins most easilyconnected to the pins of the circuit board 15 from among the plural pingroups G1 and G2. More specifically, this configuration improves generalapplicability because the positions of the device-side pins of thedevice in which the display device 2 is incorporated are not limited topredetermined positions.

Second Variation of the First Embodiment

Components of the movement 10 can be disposed on the back side part ofthe display device 2 described above. More specifically, a pressureplate for holding the drive wheel train 13 and other wheel trains andlevers can be disposed to the back side 30B of the wiring board 30. Thisenables efficiently arranging parts in a combination timepiece in whichthe display panel 20 functions as the dial, and thus enables reducingthe size of the timepiece.

Embodiment 2

A second embodiment of the invention is described next with reference toFIG. 7. FIG. 7 is a schematic section view of the display device 5according to this embodiment of the invention. A plurality of electroniccomponents 61 to 64 are mounted on the back side 30B of the wiring board50 of the display device 5. These electronic components include a drivecircuit IC 61 for the display panel 20, a temperature sensor 62, and aphotodetector 63 such as a photodiode rendering a position detectionsensor for sensing the rotational position of the wheels to which thehands 11 are attached

A plurality of pins 610 on the back side 30B of the wiring board 50 areelectrically connected through vias to the patterns 31A on the frontside 30A of the wiring board 50. Connection pins 31 that are conductiveto selected input/output pins 233 through the patterns 31A are formed onthe back side 30B of the wiring board 50.

The temperature sensor 62 is disposed at a position corresponding to theimage display area where the electrophoretic layer 22 is disposed, andthe temperature sensor 62 detects a temperature close to the temperatureof the electrophoretic layer 22. The drive circuit IC 61 controlsdriving the display panel 20 based on the temperature detected by thetemperature sensor 62.

A position detection sensor in this embodiment of the invention includesa light emitting device such as an LED (light-emitting diode) mounted onthe circuit board 15 at a position behind the wheel and pinion, and aphotodetector 63 mounted on the back side 30B of the wiring board 50 fordetecting the light emitted from the light emitting device. Thephotodetector 63 detects the light from the light emitting devicethrough a hole rendered in the wheel and pinion when the hands 11 pointto the hour. The displayed time can be adjusted by controlling drivingthe drive wheel train based on the internal time kept by the timekeepingcircuit when this hand position is detected.

The position detection sensor is not limited to an optical sensor, andcould be a magnetic sensor using a Hall effect device.

This embodiment of the invention has the following effects in additionto the effects of the first embodiment described above.

(8) Because the drive circuit IC 61 of the display panel 20 is mountedon the back side 30B of the wiring board 50, the length of the wiringpattern connecting the display panel 20 and the drive circuit can beshortened compared with a configuration in which the display panel 20drive circuit is mounted on the device-side circuit board 15. Electricalresistance is thus lower and power consumption can be reducedaccordingly.

(9) The electrophoretic characteristics of the electrophoretic particleschange with temperature, but the display quality of the display panel 20can be assured by controlling driving the display panel 20 according tothe temperature detected by the temperature sensor 62. The temperaturesensor 62 is disposed to the back side 30B of the wiring board 50 thatis layered in unison with the display panel 20, and the temperaturesensor 62 detects a temperature close to the temperature of the displaypanel 20. Driving the display panel 20 can therefore be appropriatelycontrolled based on the temperature detected by the temperature sensor62.

(10) By locating the wiring board 50 in an area on the drive wheel train13 side of the display device 5, locating the parts of the positiondetection sensor (photodetector 63) near the wheel and pinion to bedetected is easier.

A double-sided circuit board is used for the wiring board in theforegoing embodiments of the invention, but the invention is not solimited and a single-sided circuit board may be used for the wiringboard. When through-via interconnects are not rendered in the wiringboard, the conductor members may be wrapped to the back side of thewiring board and conductively connected to the input/output pins andconnector pins.

The best modes and methods of achieving the present invention aredescribed above, but the invention is not limited to these embodiments.More specifically, the invention is particularly shown in the figuresand described herein with reference to specific embodiments, but it willbe obvious to one with ordinary skill in the related art that the shape,material, number, and other detailed aspects of these arrangements canbe varied in many ways without departing from the technical concept orthe scope of the object of this invention.

Therefore, description of specific shapes, materials and other aspectsof the foregoing embodiments are used by way of example only tofacilitate understanding the present invention and in no way limit thescope of this invention, and descriptions using names of parts removingpart or all of the limitations relating to the form, material, or otheraspects of these embodiments are also included in the scope of thisinvention.

What is claimed is:
 1. A display device comprising: a display panelhaving a front substrate, an image forming unit, and a back substraterendered together in layers; a wiring board layered on a back surface ofthe back substrate, the wiring board having a front side including afront surface and a back side including a back surface; a plurality ofinput/output pins formed on a front surface of the back substrate; aplurality of patterns that are formed on a the front side of the wiringboard and are electrically connected to the plurality of input/outputpins by respective bonding wires; a plurality of connection pins thatare formed on the back side of the wiring board and are electricallyconnected to the plurality of patterns a battery positioned in an areaoverlapping the display panel when viewed in a plan view; wherein theimage forming unit is sealed between the front substrate and the backsubstrate by a sealing member positioned in an area including the outeredge part of the image forming unit; and; the plurality of input/outputpins, the bonding wires, and the plurality of patterns are covered bythe sealing member.
 2. A display device as recited in claim 1, whereinthe image forming unit contains electrophoretic particles.
 3. A displaydevice as recited in claim 1, wherein the plurality of connection pinshave through-holes passing through the wiring board.
 4. A display deviceas recited in claim 1, further comprising: a drive circuit that drivesthe display panel disposed on the back surface of the wiring board.
 5. Adisplay device as recited in claim 1, further comprising: a temperaturesensor disposed on the back surface of the wiring board.
 6. A displaydevice as recited in claim 1, wherein: the display device inincorporated in a product having a circuit board that is disposed on theback surface side of the wiring board; the wiring board and the circuitboard are pressed together with an elastic connector therebetween; andthe elastic connector includes conductors connecting the connection pinsand the circuit board, and a dielectric elastic body.
 7. A displaydevice as recited in claim 1, wherein: the plurality of connections pinsare formed at a first position and a second position on the back surfaceof the wiring board; a first pin group comprising the plurality ofconnection pins formed at the first position and a second pin groupcomprising the plurality of connection pins formed at the secondposition are formed on the back surface of the wiring board.
 8. Atimepiece comprising: the display device of claim 1; and a circuit boardlocated on the back surface of the wiring board of the display device.